Centrifugal exchangers



7, 1965 J. w. BURDETT ETAL 3,221,936

CENTRIFUGAL EXCHANGERS 5 Sheets-Sheet 1 Filed June 13, 1961 1!!! rllllillllllll FIG. 4

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INVENTORS:

J.W. BURDETT K.E. TRAlN BYzMj/W THEIR ATTORNEY FIG. 6.

1965 .1. w. BURDETT ETAL 3,

GENTRIFUGAL EXGHANGERS Filed June 13, 1961 5 Sheets-Sheet 2 FIG. 2

x INVENTORS: 67 J.W. BURDETT K.E. TRAIN THEIR ATTORNEY Dec. 7, 1965 J. W. BURDETT ETAL CENTRIFUGAL EXCHANGERS Filed June 13, 1961 IEIIHTIEJIU o 0 o oo oo o 0 e e 0 o 0 .ko o o o o o o o o o o o o o 0 0 Q}: 091 0010 0 o o o o 5 3 Sheets-Sheet 5 FIG. 8

FIG. IO

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INVENTORS:

J. W. BUR DETT K. E. TRAIN BYlM/o(% THEIR ATTORNEY United States Patent O 3,221,986 CENTRIFUGAL EXCHANGERS Joseph W. Burdett, Houston, and Kenneth E. Train, Pasadena, Tex, assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed June 13, 1961, Ser. No. 116,827 14 Claims. (Cl. 233-15) The invention relates to improvements in countercurrent-flow, centrifugal exchange devices of the type wherein fluids of different densities which are at least partially immiscible with one another flow in opposed radial directions through perforations in partition walls which surround the axis of rotation of a rotor. The purpose of such countercurrent exchange is to subject one fluid to the solvent action of the other, thereby to wash or extract a constituent or group of constituents. For example, such devices are used in the solvent refining of petroleum fractions, e.g., in extracting oil with phenol or furfural, and in the purification of chemicals and pharmaceuticals. Usually both fluids are liquid but in some applications the one of lower density may be a gas or vapor.

More particularly, the instant invention is concerned with an improved construction of the partition walls for improving the contacting efliciency.

Known centrifugal countercurrent exchangers comprise a cylindrical rotor casing mounted for rotation on a shaft and containing a plurality of radially spaced, perforated partition walls which surround the shaft substantially concentrically, i.e., which are concentric cylinders or which form a continuous spiral the turns of which are so closely spaced as to function practically as cylinders. Means, e.g., ducts communicating through the shaft, are provided for admitting the raw fluids to and discharging the contacted fluids from the rotor interior at different radial distances from the rotor shaft. Typically, the partition walls are spaced radially about 0.2 to 3 inches by the use of spacers or indentations or dimples. When the rotor is spun at 500 to 5,000 r.p.m. the centrifugal forces developed far exceed the force of gravity, so that the latter force has a negligible influence on the flow of fluids inside the rotor. The apparatus, therefore, acts in a manner analogous to a grivity-flow perforated plate extraction column without downcomers or risers, the region near the shaft corresponding to the top of such a column.

The flow rates and relative proportions of the fluid phases within the rotor are adjusted by controlling the pressure relation between the entering and exit streams. Usually this leads to a preponderance of one phase in a given space or compartment between adjacent perforated partition walls and the propenderant phase is usually continuous, i.e., it will surround droplets of the other phase as the latter flows through the perforations into the said space. Ideally, these droplets travel across the space in their settling direction (radially outwards if they are the denser fluid and radially inwards if of lower density) and may form a thin layer of coalesced fluid against the next wall before flowing through the perforations therein for dispersal within the next inter-wall compartment. Also ideally, the continuous phase moves from one interwall space to the next, without being dispersed and coalesced, in a radial direction opposite to that of the dispersed phase and thence through perforations in the next wall. It is evident that radial, as applied to flow directions, signifies only a progressive change in radial distance and does not imply straight-line flow.

It was found that, in practice, the exchange between the fluid phases or, stated otherwise, the contacting effiency attained, is often far below that expected from the known overall flow rates and properties of the fluids. Radioactive tracer tests were performed in a commercial 3,221,986 Patented Dec. 7, 1965 ICC centrifugal extractor of the type described above to determine the causes of such low efliciencies. These tests indicated the occurrence of a very high entrainment of one phase by the other, causing internal recirculation or backmixing. In some instances the total internal flow rates were five times as great as they should be for the abovestated ideal flow patterns, reckoned on the prevailing external feed rates, and this high internal entrainment is largely responsible for the low contacting efliciencies.

Due to the high rotor speeds often employed it is necessary to balance not only the physical structure but also the fluids to avoid vibrations.

It is, therefore, the principal object of this invention to improve the exchange efliciency in a centrifugal extractor of the character described above by arranging passages through the partition walls in a manner to reduce the internal entrainment or reverse flow of the phases.

A specific object is to provide an improved centrifugal extractor wherein the passages through which one of the fluid phases flows for dispersal into the other fluid phase is so formed as to provide surge spaces or chambers each of which accumulates a column or body of the former phase to a variable depth, each passage having one or more restrictive outlets, thereby regulating the flow of such phase in a manner to reduce internal recirculation.

Another object is to provide an improved centrifugal extractor wherein the partition walls are arranged to provide settling zones between imperforate regions of each pair of adjacent walls, the locations of the passages being such that the continuous phase flows successively through a dispersal zone and thence through the said settling zone and the other phase is dispersed in the said continuous phase within the dispersal zone, the two phases being, after separation, discharged into oppositely situated compartments from the downstream end of the settling zone.

Still another object is to provide a centrifugal contactor comprising a plurality of settling zones displaced in the axial direction wherein the fluids flow toward the ends of the rotor in alternate inter-wall compartments and toward the center in the intervening compartments, so as to attain an improved balance.

Other objects will become apparent from the following description.

In summary, the invention comprises two principal features which are preferably employed jointly and which will be so described, although each feature has separate utility:

First, the passages by which the disperse phase, after coalescence, leaves a given inter-wall space or compartment have walls which extend beyond the partition wall partly toward the next partition Wall in the downstream direction for the disperse phase and define surge chambers, the end of the enclosed passages being closed save for a restricted outlet which may be in the form of one or a plurality of orifices, whereby some flow resistance is created and the rate at which the said coalesced fluid moves through the passage is restricted. The flow rate is regulated by the sizes and numbers of the restricted outlets and by the height to which the coalesced fluid is collected within the surge chamber and, in some instances, outside of it, as will be described hereinafter. This makes it possible to dissipate excess pressure head and attain a hydraulic balance such as to limit or prevent internal recirculation and to dissipate the pressure at a rate which is self-regulating.

Secondly, the passages are so situated as to introduce the two fluids from different adjoining compartments into each compartment so as to effect mixing within a dispersal zone, to effect concurrent flow of the resulting dispersion through a settling zone bounded by imperforate regions of adjacent walls, and to cause the separate efflux of the settled fluids in opposite radial directions from the downstream end of the settling zone. By thus insuring orderly dispersal and effective separation of the fluid phases in the settling zone, entrainment and the tendency for internal circulation are greatly reduced.

In one form of the contactor there are at least two settling zones within each compartment between adjacent partition walls and the passages are arranged so that the fluids flow generally parallel to the rotor axis, the flow being from the axial ends of the rotor toward the center in alternate compartments and from the center toward the ends in the intervening compartments. By this arrangement an improved redistribution of the fluids is achieved, leading to improved balance and freedom from vibrations.

In another embodiment there are, within each interwall compartment, a plurality of settling zones arranged circumferentially about the rotor and the flow-direction of the fluids is circumferential, normally in a direction relative to the rotor opposite to the direction of rotation of the rotor, when the mass flow rate of the heavier phase exceeds that of the lighter phase, but usually in the same direction as the rotation when the lighter phase has a greater mass flow rate than the heavier phase. In this manner a large number of well-defined dispersal and settling zones are provided.

The invention will be further described with reference to the accompanying drawings forming a part of this specification and showing certain preferred embodiments, wherein:

FIGURE 1 is a diagrammatic perspective view of a centrifugal exchanger device, parts being broken away and stationary parts being shown in dashed lines;

FIGURE 2 is an axial sectional view through the rotor;

FIGURES 3 and 4 are fragmentary, enlarged transverse sectional views taken on the lines 3-3 and 4-4, respectively, of FIGURE 6;

FIGURE 5 is a developed view of a part of one partition plate, as it would appear from the outside if unrolled to form a flat plate;

FIGURE 6 is a diagrammatic sectional view corresponding to a part of FIGURE 2 below the axis of r0ta tion showing the parts on an enlarged scale and illustrating the flow;

FIGURE 7 is a sectional view corresponding to FIG- URE 6 and showing a modification;

FIGURE 8 is a sectional view corresponding to FIG- URE 6 showing a third embodiment;

FIGURE 9 is a developed view of part of a partition according to FIGURE 8, as viewed from the bottom toward the axis of rotation;

FIGURE 10 is a sectional view corresponding to FIG- URE 6 showing a fourth embodiment;

FIGURE 11 is a fragmentary transverse sectional view showing a fifth embodiment wherein the flow of fluids is circumferential; and

FIGURE 12 is a view corresponding to FIGURE 11 showing a sixth embodiment wherein fluid flow is also circumferential and downcomers are provided.

It will be understood that, throughout, the drawings are partly diagrammatic in that the number of partition walls shown is less than would usually be used and that the dimensions are altered for clarity.

Referring to FIGURES 1-6, the contactor comprises a supporting framework 11 which carries a rotatable shaft 12 upon which is mounted a rotor 13. As shown in dotted lines in FIGURE 1, the rotor has a stationary casing comprising upper and lower sections 14 and 15. Torque for driving the rotor is applied to a drive pulley 16. The shaft 12 has two axial bores which are interrupted at the rotor and contain smaller coaxial pipes 17 and 18, respectively, to define four channels: a pair of supply channels within the pipes 17 and 18 for the influx to the rotor of the heavier and light fluid, respcctively, and annular channels 19 and 20 for the efflux of contacted lighter and heavier fluids, respectively. The inlet ends of the pipes 17 and 18 communicate through bores in stationary caps 21 and 22 at the extremities of the shaft with inlet openings 23 and 24, respectively, suitable sealing means being provided at 25 and 26 to isolate the inflowing fluids from the outflowing fluids. Outlet pipes 27 and 28 communicate with the annular channels 19 and 20, respectively.

The rotor 13 comprises a hub 9 which is fixed to the shaft 12, and a rotor housing which includes a pair of annular end plates 29 and 30 fixed to the hub and a peripheral wall 31 to define a closed chamber. Within the rotor and spaced from the end plates with a small clearance suflicient to provide flow spaces adjacent the plates 29 and 30 are interior annular end plates 32 and 33 which are joined to the hub and terminate radially short of the wall 31. A plurality of concentric perforated partition walls 34 (sometimes further identified with letter suffixes) is mounted in radially spaced relation between the interior end plates to define a plurality of annular contacting compartments situated at progressively increasing radii. The radial dimensions of such spaces are typically between 0.2 and 3 inches. Fresh heavier fluid from the pipe 17 is admitted to a contacting compartment at a radially inner part of the rotor, but preferably not the innermost compartment, by one or more radial tubes 35 and passages 36 formed in the shaft. These tubes extend through holes in the inner partition walls with close fits. Contacted lighter fluid flows from the space immediately surrounding the hub 9 into the annular channel 19 via one or more ports 37 formed in the hub and shaft 12. Fresh lighter fluid from the pipe 18 is admitted to a contacting compartment at a radially outer part of the rotor, but preferably not to the outermost compartment, by one or more tubes 38 and pas sages 39 drilled in the end plate 33. Contacted heavier fluid flows from the space immediately adjoining the peripheral wall 31 through a radial passage 40 between the end plates 29 and 32 and also through a radial passage 40a between the end plates 30 and 33, and thence via registering ports in the hub 9 into passages 41 and 41a formed in the shaft. Flow from the passage 40 into the passages 41 and 41a occurs through an axial passage 42 milled into the hub. Vanes 43 extending generally radialy but curved like turbine blades may be provided within the passages 40 and 40a to aid in reducing the circumferential velocity of the fluid which moves radially inward, but may be omitted.

The elements described up to this point, except for the configuration of the perforated walls 34, are known per se and commercially available and are, therefore, not further described.

Considering now the invention, each of the partition walls 34 is provided with two sets of passages, 44 or 44a, and 45 or 45a, respectively, for the predominantly separate flow of the continuous fluid and the fluid to be dispersed, herein for brevity called the disperse fluid. It will be understood that either the lighter or the heavier fluid y be the disperse fluid, and that the arrangement shown, wherein the lighter fluid is assumed to be the disperse fluid, is merely illustrative; when the heavier fluid is the disperse fluid the arrangement of the passages is radlally reversed. The passages 44, 44a may be formed as downcomers, i.e., they may have lips or walls 46 which surround large, unobstructed channels to conduct the continuous fluid into the interior of the next outer contacting compartment. They are advantageously made large, to offer low flow resistance. It will be noted that each passage 44 in one wall is displaced from the passage 44a in the next wall to cause the continuous fluid to flow through a compartment via an elongated path parallel to the walls. In the embodiment under consideration this flow is generally parallel to the axis of rotation, although some circumferential flow will occur due to radial flow of the fluids. Also, as will appear from a subsequent embodiment, the lips 46 are optional.

The passages 45, 45a include surge chambers. These chambers are enclosed by confining side walls 47 which extend into the next radially inner compartment, partly to the next wall, opposite an imperforate region thereof, and end walls 48 at the downstream ends of the chambers. In this embodiment the surge chambers are annular about the rotor hub and trough-shaped. The surge cham bers should be in free communication at their upstream ends with the local compartment so as to receive coalesced disperse fluid which collects as a film on the compartment wall. Restricted outlet openings 49 are formed in the said end walls and are positioned to inject the disperse fluid from an outer compartment into the stream of continuous fluid within a given compartment soon after admission of the latter from the next inner compartment. The zone into which the openings 49 discharge is, therefore, a dispersal zone. Adjoining this zone in the downstream flow direction of the continuous fluid is a settling zone 50 which is bounded both on the radially inner and outer sides by imperfortae regions 51 of the partition walls. It will be noted that the group of passages 45 in one wall is displaced from the group of passages 45a in the next wall, whereby the disperse fluid is discharged from the compartment only after flow through the settling zone.

As is seen from FIGURES 3-5, each of the surge chambers in this embodiment is elongated circumferentially with respect to the rotor. The passages 44, 44a, are shown to be circumferentially interrupted for structural reasons but may be formed as continuous troughs (as is shown for the openings 45), the trough end walls having holes or slots of suflicient free area to offer low flow resistance. The passages 45, 45a, may be formed as continuous troughs, as shown. Any desired number of such passages may be proavided about the partition walls, as will be described in connection with FIGURE 7.

In operation, the small droplets of disperse phase in the dispersion are settled out from the continuous phase within each settling zone 50, so that the continuous fluid which flows through the passages 44, 44a, contains little or no disperse fluid. The settled disperse fluid collects along each inner wall, where it coalesces partly or completely. It enters the surge chambers of the passages 45, 45a, and collects therein to form a body of coalesced fluid because of the flow-restrictive action of the small outlets 49. When coalescence is not complete minor amounts of continuous phase may be included in the bodies. This body or column is separated from the continuous phase by an interface indicated at I, I and I" in FIGURE 6. The position of the interface may vary, e.g., be well inside the surge chamber, as shown for I, or outside of the chamber, as shown for 1". The driving force for flow of the disperse phase depends in part upon the depth of this body, so that a selfaregulating action results.

Hydraulic balance is maintained in that the pressure due to hydraulic head in the surge chambers for the coalesced disperse phase equals the flow pressure drop. Pressure due to liquid head is equal to the product of (l) the height of the coalesced disperse fluid (including, in some cases, the layer of coalesced disperse fluid outside the surge chambers as shown for I), (2) the density difference between the two fluid phases and (3) the centrifugal force. Pressure drop equals the sum of (l) the pressure drop due to flow of coalesced disperse phase through the passages 45, 45a, including their surge chainbers and their orifices, (2) pressure drop due to flow of the continuous phase and the dispersion through the settling zone, and (3) pressure drop due to flow of the continuous phase through the passages 44, 44a. By providing large passages for the continuous fluid and sufliciently wide spacings between the walls in relation to the flow rates, the frictional pressure drop through these passages is low or negligible. Therefore the frictional pressure drop required to balance the pressure due to liquid head will be principally or almost solely provided by the orifices 49.

It is evident from the foregoing that the construction according to the invention provides the following features:

(1) One phase is continuous through the extraction zone without appreciable pressure drop as it progresses from compartment to compartment through the passages 44, 44a.

(2) Passages extending in the downflow direction of the disperse phase, provided with surge chambers and orifice restrictions, regulate the flow of that phase to maintain hydraulic balance.

(3) Considerable coalescence of the dispersed phase is attained before transfer to the next compartment.

(4) A fixed flow path is provided for each phase, with separate zones for (a) dispersing and mixing, (b) settling and coalescence and (c) transfer to the next compartment.

As was previously indicated, the invention may assume different embodiments. As is shown in FIGURE 7, there may be any number of settling zones within one inter-wall compartment. In this embodiment, especially suitable for rotors which have long axial dimensions, the alternate partition walls 34. and 34h are provided with an odd number of passages 44b or downcomers for the continuous phase, e.g., one such passage, and an even number of passages 45b, 45c, e.g., two, for flow of the disperse phase. The intervening walls 34g have an even number of passages 44c, 44d, for the continuous phase and also an even number of passages 45d, 45s, for the disperse phase. The flow directions are indicated by the arrows, from which it is evident that the continuous phase supplied by the passages 44b divides into two streams which flow through the dispersal zones opposite the passages 45d and 452, respectively. The passages 45b-45e provide surge chambers and restrictive orifices as in the prior embodiment. Operation is otherwise as described for the previous embodiment.

In the construction according to FIGURE 7 the flow in alternate compartments is from the ends of the rotor toward the middle and then, after transfer to adjacent compartments, from the middle toward the rotor ends. This arrangement eliminates any tendency toward vibration by balancing the fluid forces along the axis of the rotor. The rotor is, thereby, in principle separated into two parallel contactors which are in communication with one another so that there is mixing and redistribution of the fluids of each phase at the middle of the rotor. This results in a rebalancing of the flow rates to the ends.

The surge chambers for the disperse phase may take other forms. For example, they may be formed by a multitude of crater-like projections instead, as is shown in FIGURES 8 and 9. These are shown as frusto-conical protrusions 55, 55a, having smaller orifices 56 at their downstream ends, and are positioned so that the orifices 56 are in the zones occupied by the corresponding orifices 49 in the prior embodiments. These walls may be formed integrally with the annular partition walls 34f, 34 by a simple stamping operation.

Coalesced disperse phase collects within each of these craters and the action is similar to that previously described with the diiference that each small surge chamber acts independently. As in the prior embodiments, these surge spaces dampen fluctuations in the flow rate of the dispersed phase and the interface levels I adjust them selves to establish a hydraulic head suflicient to overcome the orifice pressure drop corresponding to the flow rate.

The embodiment shown in FIGURE 10 employs the split-flow principle considered above in connection with FIGURE 7 but uses individual passages as in FIGURES 8 and 9, and omits the side walls for the continuous phase passages. Thus, the partition walls 34m, 3412, have large openings 57 and 57a, respectively, for the flow of the continuous phase, and curved crater-shaped walls 58, 58a which define the surge chambers of the disperse phase passages and have small orifices 59.

In the preceding embodiments fiow of the phases through the compartments was generally parallel to the rotor axis. The invention may also be applied to embodiments wherein the fluids flow circumferentially with respect to the rotor. The embodiments are shown in FIG- URES l1 and 12, respectively.

Referring to FIGURE 11, the partition walls 34p, 34: have large openings 60 and 60a, respectively, for the flow of the continuous phase. These openings are arranged in zones extending the full lengths of the partition (parallel to the rotor axis), these zones being spaced apart circumferentially at a suitable angle, such as 60", and each occupying a small sector, e.g., 14. The openings 60 are displaced from the openings 60a on the next wall by half the former angle, such as 30. A group of passages 61 or 61a (corresponding to the passages 45 and 45a of the first embodiment) is provided for the flow of disperse fluid in each wall between the openings 60 or 60a. Each disperse phase-passage may be formed according to any of the previous embodiments, e.g., by truncated dimples or hemispherical indentations having restricted orifices 62 to provide surge chambers.

For convenience, the term downstream direction will herein be used to denote the circumferential direction opposite to that of the arrow 63, which shows the direction of rotation of the rotor when in operation.

The passages 61 are advantageously located to one side of the midpoint between the passages 60. Thus, the latter may be displaced about 23 in the downstream direction form the former. The same relation obtains for the passages 60a and 61a. The successive Walls are assembled as shown to provide a settling space 64 bounded by imperforate portions of the walls, immediately downstream from each group of passages 61 or 61a, by which the disperse phase enters a compartment. An auxiliary settling zone 65 is formed immediately downstream of the group of passages 61 or 61a by which the disperse phase leaves the compartment.

In operation, when the rotor is spun the continuous phase (assumed to be the heavier) flows radially outwards through the passages 60 or 60a. Because of its movement away from the axis of rotation it assumes a flow in a direction relative to the walls opposite to that shown by the arrow 63, i.e., in the downstream direction. The phase flows thence past the orifices 62, through which disperse phase flows from the adjacently outer compartment to form a dispersion. Although the disperse phase, due to its inward radial movement, would it alone tend to flow in the upstream direction, it is carried downstream with the continuous phase because the latter is the preponderant phase. The resulting dispersion is settled in each settling zone 64, and major portions of the separated phases leave the compartment via the passages 60 or 60a and 61 or 61a, respectively; the remaining parts of the mixture continue to flow into the auxiliary settling zones 65, immediately downstream. A body of coalesced disperse phase collects within each of the surge chambers formed at the passages 61 and 61a in the manner described for the prior embodi- I ments. Additional settling occurs in the auxiliary settling zones 65, from which the coalesced disperse phase is discharged along the partition wall into the next light-phase riser 61 or 61a.

In the embodiment according to FIGURE 12, wherein like reference numbers denote parts as described in connection with FIGURE 11, the downstream ends of the auxiliary settling zones 65 are closed by radial barrier walls 66. Near to and spaced to the downstream side of each wall 66 is a second radial wall 67 having an opening 68 by which the continuous phase, entering via the passages 60 or 60a into the space between adjacent walls 66 and 67, enters the next compartment in a downstream direction.

The walls 66 and 67 define a downcomer and the openings 68 control the flow of the continuous phase. They prevent the circulation of this phase entirely around the partition wall. In cases where the mass flow rate of the dispersed phase occasionally equals or exceeds that of the continuous phase, the tendency for the mixture to flow downstream may be reversed. The use of the downcomers, defined by the walls 66 and 67, accelerates the flow of the continuous phase in the desired direction, thereby insuring the desir'ed flow pattern.

In regard to all of the several embodiments, it may be noted that the passages size for the continuous phase is not important so long as there is suflicient total area for flow of this phase at low velocity through the holes. Large holes, e.g., one-half inch in diameters, may be used; they would permit free flow of entrained solids with the continuous phase.

The orifices for the flow of the disperse phase are made small, e.g., 0.05 to 0.25 in diameter, to prevent flow of the continuous phase in the direction opposite to that of the disperse phase. The number of orifices is determined by the amount of total orifice area needed to pass the maximum flow rate expected at design orifice pressure drop. Typically, the surge chambers extend into the next compartment for distances between about 0.25 and 0.6 of the inter-wall space and the volume of each surge chamber may be between about two and twenty times the product of the depth of the surge chamber and the aggregate area of the restricted outlet or outlets to the said chamber. However, when troughs like those of FIGURES 1-7 are used, the surge chambers may have considerably larger volumes.

We claim as our invention:

1. In centrifugal apparatus for the countercurrent exchange of at least partially immiscible fluids of difierent densities by repeated dispersion of one in the other, the combination of:

(a) a rotor having an axial shaft mounted for rotation,

(b) a plurality of parallel, radially closely spaced partition walls within said rotor surrounding said shaft substantially concentrically and defining inter-wall compartments between juxtaposed walls,

(0) means communicating with the interior of said rotor for supplying the denser fluid to and discharging the less dense fluid from the rotor interior at the radially inner portion thereof, and means communicating with the interior of said rotor for discharging the denser fluid from and admitting the less dense fluid to the rot-or interior at the radially outer portion thereof,

(d) said partition walls having two sets of passages for the predominantly separate flows of said fluids through the passages of the respective sets,

(1) said passages being situated in said partition walls opposite imperforate areas in the respectively opposite partition walls, each inter-wall compartment having at least one inlet passage of each of said sets formed in opposite walls and relatively positioned to disperse the fluid that flows through the first set of passages into the other fluid to form a dispersion,

(2) each said inter-wall chamber having at least one outlet passage of each of said sets formed in opposite walls and spaced from said inlet passages by an intermediate settling zone which is bounded by imperforate wall regions for the flow of said dispersion through said Zone,

(3) the passages of the said first set including surge chambers enclosed by chamber walls which extend from the respective partition walls into the contiguous inter-wall compartments in the radial flow direction of said fluid which is dispersed for 9 distances less than the depths of said inter-wall compartments, and (4) each said enclosed chamber having at the radial downstream end thereof an outlet opening which is restricted in relation to the area of said enclosed chamber, whereby bodies of said fluid that is dispersed can, after coalescence, collect within said chambers.

2. Centrifugal apparatus according to claim 1 wherein the depth of each said surge chamber into the said contiguous compartment is between 0.25 and 0.6 of the radial extent of said contiguous inter-wall compartment and the volume of each surge chamber is at least twice the product of the said depth and the total area of the outlet opening.

3. Centrifugal apparatus as defined in claim 1 wherein said surge chambers for coalesced fluid are formed by crater-shaped projections which extend from each partition wall, each said projection having at its apex a single orifice that is restricted in relation to the area of the corresponding surge chamber.

4. Centrifugal apparatus as defined in claim 1 wherein the said passages are distributed circumferentially about the partition walls and the said inlet passages to each said compartment are displaced from the said outlet in a direction substantially parallel to the rotor shaft, whereby the flow directions of the dispersions through settling zones are substantially parallel to the rotor shaft.

5. Centrifugal apparatus as defined in claim 1 wherein the said passages are distributed along the several partitions in zones parallel to the rotor axis and the said inlet passages to each said compartment are displaced circumferentially from said outlet passages, whereby the flow direction of the dispersion through the settling zones are circumferential with respect to the rotor.

6. In centrifugal apparatus for the countercurrent exchange of at least partially immiscible fluids of diflerent densities by repeated dispersion of one in the other, the combination of:

(a) a rotor having an axial shaft mounted for rotation,

(b) a plurality of parallel, radially closely spaced partition walls within said rotor surrounding said shaft substantially concentrically and defining inter-wall compartments between juxtaposed walls,

(c) means communicating with the interior of said rotor for supplying the denser fluid to and discharging the less dense fluid from the rotor interior at the radially inner portion thereof, and means communicating with the interior of said rotor for discharging the denser fluid from and admitting the less dense fluid to the rotor interior at the radially outer portion thereof,

(d) said partition walls having two sets of passages for the predominantly separate flows of said fluid through the passages of the respective sets,

(1) said passages being positioned to provide within each said inter-Wall compartment a settling zone that is bounded by imperforate regions of juxtaposed partition walls, there being for each said settling zone at least one inlet passage of the second set in one wall and an inlet passage of the first set in the other wall positioned to disperse fluid flowing through the said first inlet passage into the fluid admitted through the first-mentioned inlet passage before entering the said settling zone, said inlet passages being at the upstream ends of said settling zones,

(2) there being, further, for each said settling zone at the downstream end thereof at least one exit passage of the first set in said first-mentioned wall and at least one exit passage or" the second set in the latter wall.

7. Centrifugal apparatus as defined in claim 6 wherein the said settling zones are oriented with the upstream and downstream directions thereof substantially parallel to the said rotor shaft.

8. Centrifugal apparatus as defined in claim 6 wherein there is a plurality of settling zones, each provided with the specified inlet and exit passages in the partition walls, between each pair of walls, said settling zones being spaced along a line parallel to the rotor shaft.

9. Centrifugal apparatus as defined in claim 8 wherein the said settling zones are oriented with the upstream and downstream directions substantially parallel to the said rotor shaft, the said upstream ends of the settling zones within alternate inter-wall compartments being situated at the rotor ends for flow of fluid, thence toward the center of the rotor and the settling zones within intervening inter-wall compartments being situated at the center of the rotor for flow of fluid thence toward the rotor ends, the several settling zones within each said compartment being in intercommunication.

10. Centrifugal apparatus as defined in claim 6 wherein the said settling zones are oriented with the direction between said upstream and downstream ends thereof extending substantially circumferentially with respect to said partition walls.

11. In centrifugal apparatus for the countercurrent exchange of at least partially immiscible fluids of different densities by repeated dispersion of one in the other, the combination of:

(a) a rotor having an axial shaft mounted for rotation,

(b) a plurality of parallel, radially closely spaced partition walls within said rotor surrounding said shaft substantially concentrically and defining inter-wall spaces between juxtaposed walls,

(c) means communicating with the interior of said rotor for supplying the denser fluid to and discharging the less dense fluid from the rotor interior at the radially inner portion thereof, and means communicating with the interior of said rotor for discharging the denser fluid from and admitting the less dense fluid to the rotor interior at the radially outer portion thereof,

(d) said partition walls having two sets of passages for the predominantly separate flows of said fluids through the passages of the respective sets with dispersal of the fluid which flows through the first set of passages into the other fluid which is situated in the respectively contiguous inter-wall space and for the subsequent coalescence of the dispersed fluid after traversing the said inter-wall space,

(1) each of said passages being situated opposite an imperforate area in the respectively opposite partition wall,

(2) the passages of said first set including troughshaped surge chambers enclosed by confining side walls that extend from the respective partition walls into the contiguous inter-wall space in the radial flow direction of said fluid which is dispersed for distances less than the depths of said inter-wall spaces, and

(3) each said enclosed chamber having at the bottom ends of said side walls an orifice wall having a substantially cylindrical contour, there being a plurality of orifices in each said orifice wall distributed circumferentially and restricted in relation to the area of the chamber, whereby a body of said coalesced fluid can collect within said chambers.

12. Apparatus according to claim 11 wherein said trough-shaped chambers extend through 360 about each partition wall.

13. In a centrifugal apparatus for the countercurrent exchange of at least partially immiscible fluids of different densities by repeated dispersion of one in the other, the combination of:

(a) a rotor having an axial shaft mounted for rotation,

(b) a plurality of parallel, radially closely spaced partition walls within said rotor surrounding said shaft substantially concentrically and defining inter-wall spaces between juxtaposed walls,

(c) means communicating with the interior of the (d) said partition walls havlng two sets of passages for the predominantly separate flows of said fluids through the passages of the respective sets,

(1) said passages being positioned to provide within the said inter-wall spaces between each pair of partition walls at least two settling zones that are bounded by imperforate regions of juxtaposed walls, there being for each said settling zone an inlet passage of the second set in one wall and an inlet passage of the first set in the other wall positioned to disperse fluid flowing through the latter passage into the fluid admitted through. the first-mentioned inlet passage, said inlet passages being at the upstream ends of said settling zones,

(2) there being, further, for each said settling zone an exit passage of the first set in said firstmentioned wall and an exit passage of the second set in the second-mentioned wall, both exit 12 municating with the interior of said rotor for discharging the denser fluid from and admitting the less dense fluid to the rotor interior at the radially outer portion thereof,

(d) said partition walls having two sets of passages for the predominantly separate flows of said fluids through the passages of the respective sets,

(1) said passages being positioned to provide within the inter-wall space between each pair of partition walls a settling zone that is bounded by imperforate regions of juxtaposed walls and is oriented with the upstream and downstream directions thereof substantially circumferential with respect to the partition walls, there being for each settling zone an inlet passage for admitting one fluid to said space formed in one of said juxtaposed walls at the upstream end of the settling zone and an exit passage for the same fluid in the other of said juxtaposed walls at the downstream end of said zone,

(2) there being, further, an inlet passage to said space for the other fluid formed in the said other wall and having a restricted orifice and situated at the upstream end of the settling zone for the dispersal of the said other fluid into said one fluid before entering the settling zone, and an exit passage for the said other fluid formed in the said one wall at the downstream end of the settling zone, and

passages being situated at axially spaced points of the partition walls relative to the inlet passages and at the downstream ends of the settling zone and the said upstream and downstream directions through said zones are substantially parallel to the rotor axis,

(e) a radial barrier wall situated at the downstream end of each settling zone.

References Cited by the Examiner UNITED STATES PATENTS (3) the several settling zones within each inter- 587,171 7/1897 Beach 233-37 wall space being in intercommunication and hav- 2,202,071 5/ 1940 Van Dongen et a1, 261-114 ing opposed flow directions, the flow directions 2 2 157 942 P d i i k 2 1 3 within alternate inter-wall spaces being from the 40 2,291,849 94 Tomlinson axial ends of the rotor toward the center and, 2,460,019 1/1949 Long et a1. is fg ggs gg f zgz fi from the center 2,486,630 11/1949 Brown 23 270.5 14. In centrifugal apparatus for the countercurrent exgig ZZ 1%; change of at least partially immiscible fluids of diflerent 2747849 5/1956 C 1b '1; densities by repeated dispersion of one in the other, the 0 a combination of: 2,758,783 8/ 1956 Podb eln ak 23315 (a) a rotor having an axial shaft mounted for rotation, 2,758,784 8/1956 podblelniak et a1 233-15 (b) a plurality of parallel, radially closely spaced par- 2,840,301 Podblelmak 233i15 tition walls within said rotor surrounding said shaft FOREIGN PATENTS substantially concentrically and defimng inter-wall 233,878 5/1925 Great Britain spaces between juxtaposed walls,

(c) means communicating with the interior of said rotor for supplying the denser fluid to and discharging the less dense fluid from the rotor interior at the radially inner portion thereof, and means com- M. CARY NELSON, Primary Examiner.

HERBERT L. MARTIN, HARRY B. THORNTON, Examiners. 

1. IN CENTRIFUGAL APPARATUS FOR THE COUNTERCURRENT EXCHANGE OF AT LEAST PARTIALLY IMMISIBLE FLUIDS OF DIFFERENT DENSITIES BY REPEATED DISPERSION OF ONE IN THE OTHER, THE COMBINATION OF: (A) A ROTOR HAVING AN AXIALLY SHAFT MOUNTED FOR ROTATION, (B) A PLURALITY OF PARALLEL, RADIALLY CLOSELY SPACED PARTITION WALLS WITHIN SAID ROTOR SURROUNDING SAID SHAFT SUBSTANTIALLY CONCENTRICALLY AND DEFINING INTER-WALL COMPARTMENTS BETWEEN JUXTAPOSED WALLS, (C) MEANS COMMUNICATING WITH THE INTERIOR OF SAID ROTOR FOR SUPPLYING THE DENSER FLUID TO AND DISCHARGING THE LESS DENSE FLUID FROM THE ROTOR INTERIOR AT THE RADIALLY INNER PORTION THEREOF, AND MEANS COMMUNICATING WITH THE INTERIOR OF SAID ROTOR FOR DISCHARGING THE DENSER FLUID FROM AND ADMITTING THE LESS DENSE FLUID TO THE ROTOR INTERIOR AT THE RADIALLY OUTER PORTION THEREOF, (D) SAID PARTITION WALLS HAVING TWO SETS OF PASSAGES FOR THE PREDOMINANTLY SEPARATE FLOWS OF SAID FLUIDS THROUGH THE PASSAGES OF THE RESPECTIVE SETS, (1) SAID PASSAGES BEING SITUATED IN SAID PARTITION WALLS OPPOSITE IMPERFORATE AREAS IN THE RESPECTIVELY OPPOSITE PARTITION WALLS, EACH INTER-WALL COMPARTMENT HAVING AT LEAST ONE INLET PASSAGE OF EACH OF SAID SETS FORMED IN OPPOSITE WALLS AND RELATIVELY POSITIONED TO DISPERSE THE FLUID THAT FLOWS THROUGH THE FIRST SET OF PASSAGES INTO THE OTHER FLUID TO FORM A DISPERSION, (2) EACH SAID INTER-WALL CHAMBER HAVING AT LEAST ONE OUTLET PASSAGE EACH OF SAID SETS FORMED IN OPPOSITE WALLS AND SPACED FROM SAID INLET PASSAGES BY AN INTERMEDIATE SETTLING ZONE WHICH IS BOUNDED BY IMPERFORATE WALL REGIONS FOR THE FLOW OF SAID DISPERSION THROUGH SAID ZONE, (3) THE PASSAGES OF THE SAID FIRST SET INCLUDING SURGE CHAMBERS ENCLOSED BY CHAMBER WALLS WHICH EXTEND FROM THE RESPECTIVE PARTITION WALLS INTO THE CONTIGUOUS INTER-WALL COMPARTMENTS IN THE RADIAL FLOW DIRECTION OF SAID FLUID WHICH IS DISPERSED FOR DISTANCES LESS THAN THE DEPTHS OF SAID INTER-WALL COMPARTMENTS, AND (4) EACH SAID ENCLOSED CHAMBER HAVING AT THE RADIAL DOWNSTREAM END THEREOF AN OUTLET OPENING WHICH IS RESTRICTED IN RELATION TO THE AREA OF SAID ENCLOSED CHAMBER, WHEREBY BODIES OF SAID FLUID THAT IS DISPERSED CAN, AFTER COALESCENCE, COLLECT WITHIN SAID CHAMBERS. 